Wireless access schemes and wireless networks of cellular mobile communication (hereinafter also referred to as LTE-Advanced (LTE-A), LTE-Advanced Pro (LTE-A Pro), or Evolved Universal Terrestrial Radio Access (EUTRA)) are under review in 3rd Generation Partnership Project (3GPP). Further, in the following description, LTE includes LTE-A, LTE-A Pro, and EUTRA. In LTE, a base station device (base station) is also referred to as an evolved Node B (eNodeB), and a terminal device (a mobile station, a mobile station device, or a terminal) is also referred to as a user equipment (UE). LTE is a cellular communication system in which a plurality of areas covered by a base station device are arranged in a cell form. A single base station device may manage a plurality of cells.
LTE is compatible with frequency division duplex (FDD) and time division duplex (TDD). LTE employing the FDD scheme is also referred to as FD-LTE or LTE FDD. TDD is a technology which enables full duplex communication to be performed in at least two frequency bands by performing frequency division multiplexing on an uplink signal and a downlink signal. LTE employing the TDD scheme is also referred to as TD-LTE or LTE TDD. TDD is a technology that enables full duplex communication to be performed in a single frequency band by performing time division multiplexing on an uplink signal and a downlink signal. The details of FD-LTE and TD-LTE are disclosed in Non-Patent Literature 1.
The base station device maps a physical channel and a physical signal to physical resources configured on the basis of a predefined frame configuration and transmits the physical channel and the physical signal. The terminal device receives the physical channel and the physical signal transmitted from the base station device. In LTE, a plurality of frame configuration types are specified, and data transmission is performed using physical resources of a frame configuration corresponding to each frame configuration type. For example, a frame configuration type 1 is applicable to FD-LTE, and a frame configuration type 2 is applicable to TD-LTE. The details of the frame structure are disclosed in Non-Patent Literature 1.
In LTE, a predetermined time interval is specified as a unit of time in which data transmission is performed. Such a time interval is referred to as a transmission time interval (TTI). For example, the TTI is one millisecond, and in this case, one TTI corresponds to one sub frame length. The base station device and the terminal device perform transmission and reception of the physical channel and/or the physical signal on the basis of the TTI. The details of the TTI are disclosed in Non-Patent Literature 2.
Further, the TTI is used as a unit specifying a data transmission procedure. For example, in the data transmission procedure, a hybrid automatic repeat request-acknowledgment (HARQ-ACK) report indicating whether or not received data has been correctly received is transmitted after a period of time specified as an integer multiple of the TTI after data is received. Therefore, a period of time (delay or latency) necessary for data transmission is decided depending on the TTI. Such a data transmission procedure is disclosed in Non-Patent Literature 3.